Ileal and total tract digestibility in growing pigs fed cassava root meal diets with inclusion of fresh, dry and ensiled sweet potato ( Ipomoea batatas L. (Lam.)) leaves

Abstract

Ileal and total tract digestibility in growing pigs fed cassava root meal (CRM) based diets with inclusion of fresh, dry and ensiled sweet potato leaves was studied in a 4×4 Latin square design. Four diets were formulated with CRM and casein (CAS), fresh sweet potato leaves (FSP), dry sweet potato leaves (DSP) and ensiled sweet potato leaves (ESP). The control diet (CAS) contained 100 g casein per kg DM. The experimental diets FSP, DSP, and ESP contained 350, 350 and 400 g DM of fresh, dry and ensiled sweet potato leaves per kg DM diet, respectively. Leaves were separated manually from stems and only the leaf part was used. The daily feed intakes of dry matter (DM) and dietary components were significantly different between diets ( P<0.05). There was no difference in ileal apparent digestibility of OM between diets ( P>0.05), while the total tract apparent digestibility of OM and crude protein (CP) was higher on diet CAS than on diets FSP, DSP and ESP ( P<0.05). The ileal apparent digestibility of CP and essential amino acids (EAA), except for arginine, threonine and tyrosine, were higher for diet CAS than for diets FSP, DSP and ESP ( P<0.05). The ileal digestibility of NDF and the total tract digestibility of crude fibre (CF) were lower for diet CAS than for diets FSP, DSP and ESP ( P<0.05). There were no differences ( P>0.05) in digestibility of OM, CP, CF, NDF, ADF and most EAA among sweet potato leaf diets. However, there was a tendency ( P=0.064) of a lower ileal apparent digestibility of lysine in the dried and ensiled sweet potato leaves. It was concluded that, sweet potato leaves have the potential to improve dietary protein and amino acid supply in low fibre diets for pigs. Further, the optimum strategy for preserving sweet potato leaves can be decided on from consideration of the prevailing climatic conditions, as the general nutritional properties were similar for fresh, sun-dried and ensiled sweet potato leaves.